Accelerating pump



March 18, 1941. H. A. CARLSON 2,235,797

ACCELERATING PUMP Filed May 6, 1938 FIG.3. 7

INVENTOR. H AROLD A, CARLSO N M J uEQ ATTORNEY.

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Patented Mar. 18. 1941 PATENT OFFICE ACCEIERATING PUMP Application May6, 1939. Serial No. 272,124

' 40mins. (01.261-34) invention relates to internal combustion enginecarburetors and more particularly to accelerating devices to be used inconnection therewith.

Auxiliary fuel is injected into the air stream in present daycarburetors during engine acceleration when sufliclent fuel fromaspirating nozzles cannot be obtained due to low air velocities throughthe carburetor or to low fuel levels in the aspirating nozzles due topull back by interconnected idling fuel passages.

This auxiliary fuel is usually referredto as accelerating discharge andis most commonly provided by areciprocating plunger type accelcratingdevice interconnected by link mechanism to the carburetor throttle andadapted to discharge into the main air passage through the carburetorupon opening movements of the throttle. I V l it is obvious that in anautomotive-type engine driving a vehicle, the air velocity through thecarburetor which immediately ensues upon an opening movement of thethrottle from a near closed or idling position with a. conunensurateengine speed, will. be low as compared to the immediate resultingvelocity following a throttle opening movement from say, a. half openposition with the normal corresponding engine speed.

Also it is evident in'the latter instance'that fuel will he flowing fromthe aspirating nozzle and that it possesses some momentum, whereas inthe former instance an interval will be required to lift the fuel fromsome point below the point of discharge of the aspirating nozzle.

it has been found that in the operation of modern automotive internalcombustion engines, this auxiliary fuel as supplied by an acceleratingdevice is not required for throttle opening movements beyond a certainthrottle open position. For economical reasons it is, therefore,advantageous to provide a. means of conserving the fuel during thosethrottle opening movements in which it is not required.

lit is an.- object of this inventionv to providean accelerating deviceof the above character in movements in which such auxiliary fuel is notrequired.

Other objects and advantages will appear upon referring to the followingdescription and accompanying drawing in which Fig. 2 is a fragmentaryview of the carburetor shown in Fig. 1 embodying a modification pf myinvention.

Fig. 3 is also a fragmentary view of the carburetor shown in Fig. 1embodying still another modification of my invention.

Referring to Fig. l, the referencenumeral i indicates a main carburetorbody member having a mixing conduit 2 formed therein. A constant levelfuel chamber 3 also formed in the main body member is provided and aconstant level of fuel as indicated by thedot-da sh line the float 4 andthrottle valve i l suitably attached for rotation with throttle shaft itas with screws l3.

Fuel for acceleration is supplied by an accelerating device comprising acylindrical chamber l3 having a plunger it arranged for reciprocationtherein. Motion is imparted to the plunger it upon movement of thethrottle valve by means of the plunger shaft it, link, lever I'll whichis pivoted at it, link l9 and lever 20 which is rigidly attached tothe'throttle shaft l2.

Upon the intake or upward stroke of th plunger it, fuel flows into thechamber it from the constant level chamber 3 through the valvecontrolled passage it around the spring retained combination intake andby-pass valve it, fuel passages 23 and M and opening iii.

0n the downward or discharge stroke of the plunger it fuel is forcedthrough opening it, passage 2% around gravity discharge valve ii throughpassages 2t and 2t and is discharged into the mixing conduit and the airstream through discharge nozzle 30 and orifice 51!.

In order to divert the fuel from the mixing conduit at a predeterminedthrottle position, I have provided the valve pin 3! which is guided inthe casting t and held normally in the position shown by the spring 32.a

A lug 33 on lever l'l engages the pin St at some predetermined throttleposition and any further opening movement of the throttle will cause pin3| to be moved downwardly thereby forcing valve 22v downward and off itsseat. The spring 3 which normally holds valve 22 on its seat iscalibrated to permit the proper functioning of,valve 22 as an intakecheck valve...

Passages 35 and 36 in the plunger shaft H: are provided to relievepressure in the chamber l3 which may result from vaporization of thefuel therein due to absorption of heat from surrounding engine parts andwhich would, if not relieved, cause untimely discharge of fuel into themixing conduit. It will be understood that passage 36 in plunger shafti5 is relatively small and the amount of fuel escaping therethroughduring a discharge stroke is negligible.

A slot 31 in the wall I3 extending to a point below the level of fuel isprovided to supply fuel to chamber l3 above the plunger l4 at all timesthereby insuring a liquid seal for the plunger.

In the modification disclosed in Fig. 2 separate valves are provided forintake and by-pass control. Other associated elements similar to thoseshown in the device of Fig. l are indicated by similar numerals. Theby-pass valve 38 in this arrangement is provided with a verticallyextending stem 39 which is engaged by the plunger l4 at somepredetermined throttle position after which any further throttle openingmovement will force valve 33 downward causing the fuel to be by-passedback into the chamber 3, through openings 40 around valve 38 throughpassages 4|, 42 and 43.

It will be understood that the spring 44 which normally urges valve 38upward in engagement engines and carburetors.

Referring to Fig. 2 on the upward or intake stroke fuel enters chamberI3 from the constant level bowl 3 through passages 43 and 42 around thegravity intake check 45 and through opening 46.

On the downward or discharge stroke fuel is discharged through opening41, into the mixing conduit in a manner as previously described.

In the modification shown in Fig. 3 a by-pass valve 48 is provided andnormally held in engagement with its seat in passage 49 through plunger50 by the spring 5|.

A standard or pin 52 rigidly positioned at the bottom of chamber 13forces valves 48 from its seat at a predetermined throttle position,permitting the fuel to be by-passed back into chamber 3 through passages49 in plunger 50, passages 53 and 54 in plunger rod 55 and slot 31 inthe wall of chamber l3.

Fuel enters chamber l3 on the intake stroke through opening 55 aroundgravity intake check 45 and passage 46 and is discharged into the mixingconduit through similar passages as shown in Figs. 1 and 2.

It will be understood that the orifice 51 in the discharge nozzle 30 isrelatively small when compared with the net opening of the by-pass sothat a relatively small amount of fuel is discharged therethrough afterthe by-pass valve is opened.

In operation fuel is supplied to the carburetor through inlet passages53 and 53 and a substantially constant level of fuel is maintained inthe chamber 3 by the float 4 and the needle 5,

Fuel for normal and high speed operation is supplied through orifice 50,passages BI, 62 and 83 and discharges into the mixing conduit at 64.

Fuel for idling or substantially closed throttle operation is suppliedthrough orifice 65, passages 66, 61, restricting passage 63, passages69, 10, ll, 12, I3, 14 and discharges near the edge of throttle plate l3through port I5.

Upon throttle opening movements the accelerating device plunger iscaused to move down in a manner described thereby discharging fuel foracceleration into the mixing conduit. As the throttle reaches apredetermined point the bypass valve is positively opened and anyfurther discharge from the accelerating chamber is diverted.

On closing movements of the throttle, fuel is drawninto the acceleratingchamber from the constant level chamber by the upward movement of theplunger. The detailed drawings and description are intended to beillustrative and not limiting, and the exclusive use of all modi;fications which come within the scope of the appended claims iscontemplated.

I claim:

I. In a carburetor, a mixture conduit, a constant level fuel bowl, athrottle in said conduit, aspirating fuel passage means connecting saidfuel bowl with said conduit, an accelerating pump including a movablepart and a working chamber, a passage connecting said working chamberwith said fuel chamber and a more restricted discharge passage openinginto said mixture conduit, a resiliently seated valve in saidfirst-mentioned passage and an outwardly opening check valve in saiddischarge passage, a positively operating connection between saidthrottle and the movable part of said pump, and means actuated bymovement of said movable part to positively unseat the valve in saidconnecting passage in coordination with discharging movement of saidpump beyond a predetermined point whereby substantially the remainder ofthe pumped fuel is by-pas'sed through said connecting passage.

2. A carburetor as specified in claim 1 in which said connecting passageconstitutes the sole inlet connection between the pump and said fuelchamber, the valve therein being responsive to charging movement of saidpump for admitting fuel to the pump.

,3. A carburetor as specified in claim 1 including at least two passagesconnecting said working chamber with said fuel chamber, there being apressure responsive valve in one of said passages operable upon chargingmovement of said pump movable part to admit fuel to said workingchamber, said resiliently seated valve being located in a second one ofsaid connecting passages.

4. A carburetor as specified in claim 1 in which said connecting passageextends through said pump movable part, there being additionallyprovided a fixed abutment projecting from a wall of said working chamberpositioned to be engaged by said resiliently seated valve for unseatingthe same.

HAROLD A. CARLSON.

